使用 POI创建一个简单的 Excel 文件

初级程序员一枚,看到公司大佬写的生成Excel文件,做下记录,同时也分享给大家参考

  ·······································实现原理是用workBook 然后还有OutputStream

首先是一个ExcelDataBean 这个实体类 用来 声明 Excel的最大行数,最大列数 以及用来保存  所传入的 标题列 内容列 并且对它们做出校验。

import java.util.ArrayList;
import java.util.List;

/**
 * 使用 Excel007Util 工具类创建 Excel 2007 文件所需要的数据类.
 * 包含多个包含标题信息的头列表
 * 和多个内容行列表.
 * 超出 Excel 文件行列限制时会抛出异常, 不过没测试过这么大的数据.
 *
 * Created by gongsidalao on 17-5-10.
 */
public class ExcelDataBean {

    /**
     * 2007的是1048576行、16384列.
     */
    public static final int MAX_ROW_SIZE = 1048576;
    public static final int MAX_COL_SIZE = 16384;

    private List<List<?>> headerList;
    private List<List<?>> rowList;

    public List<List<?>> getHeaderList() {
        return headerList;
    }

    public List<List<?>> getRowList() {
        return rowList;
    }

    private ExcelDataBean(List<List<?>> headerList, List<List<?>> rowList) {
        this.headerList = headerList;
        this.rowList = rowList;
    }

    public static class Builder {
        private List<List<?>> headerList;
        private List<List<?>> rowList;

        public Builder() {
            headerList = new ArrayList<>();
            rowList = new ArrayList<>();
        }

        public Builder addHeaderList(List<?> header) {
            if (header.size() > MAX_COL_SIZE) {
                throw new RuntimeException("数据列超出 Excel 允许的最大值!");
            }
            if (headerList.size() + rowList.size() + 1 > MAX_ROW_SIZE) {
                throw new RuntimeException("数据行超出 Excel 允许的最大值!");
            }
            this.headerList.add(header);
            return this;
        }

        public Builder addRowList(List<?> row) {
            if (row.size() > MAX_COL_SIZE) {
                throw new RuntimeException("数据列超出 Excel 允许的最大值!");
            }
            if (headerList.size() + rowList.size() + 1 > MAX_ROW_SIZE) {
                throw new RuntimeException("数据行超出 Excel 允许的最大值!");
            }

            this.rowList.add(row);
            return this;
        }

        public ExcelDataBean build() {
            return new ExcelDataBean(headerList, rowList);
        }
    }
}

 然后下面就是一个工具类了 ,用于生成行row 生成单元格cell然后数据填充

import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;

import java.io.IOException;
import java.io.OutputStream;
import java.time.LocalDateTime;
import java.time.ZoneId;
import java.util.*;
import java.util.stream.IntStream;

/**
 * 使用 POI 创建一个简单的 Excel 文件
 * Created by gongsidalao on 17-5-10.
 */
public class Excel2007Util {


    /**
     *
     * @param excelDataBean
     * @param outputStream
     * @throws IOException
     */
    public static void createExcel(final ExcelDataBean excelDataBean,
                                   final OutputStream outputStream) throws IOException {

        //创建工作簿对象用于创建Sheet
        final Workbook workbook = new XSSFWorkbook();

        //创建一个Sheet(纸)对象也就是一个EXCEL
        final Sheet sheet = workbook.createSheet();
        //标题行数据List
        final List<List<?>> headerList = excelDataBean.getHeaderList();
        //根据标题列的大小创建几个带有标题行的Sheet
        IntStream.range(0, headerList.size())
                .forEach(i ->
                        createRow(i, 0, headerList, sheet ));
      //行偏移量用于创建数据行的时候 做行偏移处理 如果只有一个标题行的话可以写死为1
        final int rowOffset = headerList.size();
        final List<List<?>> rowList = excelDataBean.getRowList();

        IntStream.range(0, rowList.size())
                .forEach(i ->
                        createRow(i, rowOffset, rowList, sheet ));


        workbook.write(outputStream);

    }
    //创建行
    private static void createRow(final int index, final int rowOffset,
                                  final List<List<?>> rowList,
                                  final Sheet sheet) {
        List<?> data = rowList.get(index);
        if (Objects.nonNull(data) && !data.isEmpty()) {
            final Row row = sheet.createRow(index + rowOffset);
            IntStream.range(0, data.size())
                    .forEach(j ->
                        createCell(j, data, row));
        }
    }
   //创建单元格 并且填充data
    private static void createCell(final int index, final List<?> data, final Row row) {

        final Object obj = data.get(index);
        final Cell cell = row.createCell(index);
        if (obj == null) {
            cell.setCellValue("");
        } else if (Double.class.isInstance(obj)) {
            cell.setCellValue((double) obj);
        } else if (Date.class.isInstance(obj)) {
            Date date = (Date) obj;
            cell.setCellValue(LocalDateTime.ofInstant(date.toInstant(), ZoneId.systemDefault()).toString());
        } else if (Calendar.class.isInstance(obj)) {
            cell.setCellValue((Calendar) obj);
        } else if (Boolean.class.isInstance(obj)) {
            cell.setCellValue((boolean) obj);
        } else {
            final CreationHelper createHelper = row.getSheet().getWorkbook().getCreationHelper();
            cell.setCellValue(createHelper.createRichTextString(obj.toString()));
        }
    }
}

  附上一个测试类以便测试

import org.junit.Test;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.*;

/**
 * Created by gongsidalao on 17-5-11.
 */
public class Excel2007UtilTest {


    @Test
    public void TestUtil() {

        List<String> header = Arrays.asList("姓名", "年龄", "生日", "记录创建时间", "婚否", "备注");

        List<Object> list1 = new ArrayList<>();
        list1.add("AA");
        list1.add(18);
        list1.add(Calendar.getInstance());
        list1.add(new Date());
        list1.add(true);
        list1.add(null);

        List<Object> list2 = new ArrayList<>();
        list2.add("BB");
        list2.add(18);
        list2.add(Calendar.getInstance());
        list2.add(new Date());
        list2.add(true);
        list2.add(null);
        System.out.println(list1.get(0));
        String url = "L:/ceshi.xlsx";
        try (OutputStream outputStream = new FileOutputStream(url)) {
            ExcelDataBean excelDataBean = new ExcelDataBean.Builder()
                    .addHeaderList(header)
//                  .addHeaderList(header)
                    .addRowList(list1)
                    .addRowList(list2)
                    .build();

            Excel2007Util.createExcel(excelDataBean, outputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

  有什么不足的还望大家指出来,高手轻喷,做个日常记录以便学习.